Collaborations : G. Coupier, C. Minetti (ULB Brussels), C. Misbah, X. Grandchamp, A. Srivastav, V. Vitkova, M. Mader.
Shear-induced diffusion in suspensions of red blood cells.
Hydrodynamic interactions and collisions between red blood cells in flow lead to a phenomenon of shear-induced diffusion at the scale of the suspension. This phenomenon is anisotropic and non linear (the diffusion coefficient depends on the frequency of interactions, therefore on concentration and local shear rate). It plays a role in the structuration of blood flow in the microcirculation and is sensitive to mechanical properties of red blood cells, that can notably be affected by specific pathologies. The widening of a stream of red blood cells in channel flow is characterized by a sub-diffusive behaviour with exponent 1/3, a generic phenomenon in systems dominated by pairwise hydrodynamic interactions.
Related publication :
Lift and down-gradient shear-induced diffusion in red blood cell suspensions. X. Grandchamp, G. Coupier, A. Srivastav, C. Minetti and T. Podgorski, Phys. Rev. Lett. 110 (10), 108101 (2013) Abstract
Lift and migration of vesicles and red blood cells
In blood microcirculation, it is known since Poiseuille (1836) that red blood cells move away from walls to leave a depletion layer that facilitates blood flow.
The formation of this depletion layer (Fahraeus-Lindquist effect) is responsible for a decrease of the apparent viscosity of blood in capillaries, and impacts on the distribution of red blood cells in the bifurcations of the microcirculatory network. Experiments in microgravity (CNES and ESA parabolic flights) allowed a quantitative characterization of this effect on vesicles and red blood cells in shear flow near a wall. The symmetry breaking of these soft objects under flow leads to a lift force that does not exist for spherical particles in Stokes flow. In a channel flow, a second effect contributes to the migration of vesicles or cells towards the center of the channel : the non-uniformity of shear rate in Poiseuille flow.
Related publications :
Hydrodynamic lift of vesicles under shear flow in microgravity.
N. Callens, C. Minetti, G. Coupier, M. -A. Mader, F. Dubois, C. Misbah and T. Podgorski, Europhys. Lett. 83, 24002 (2008)
Non- inertial lateral migration of vesicles in bounded Poiseuille flow.
G. Coupier, B. Kaoui, T. Podgorski and C. Misbah, Phys. Fluids. 20, 111702 (2008)
Vesicles and red blood cells in flow : From individual dynamics to rheology.
P. M. Vlahovska, T. Podgorski and C. Misbah, C. R. Physique 10, 775–789 (2009)
Micro-macro link in the effective viscosity of red blood cell and vesicle suspensions.
We report on the rheology of a dilute suspension of red blood cells (RBC) and vesicles. The viscosity of RBC suspensions reveals a previously unknown signature : it exhibits a pronounced minimum in the vicinity of the tank-treading (TT)–tumbling (TB) bifurcation. This bifurcation is triggered by varying the viscosity of the ambient fluid. It is found that the intrinsic viscosity of the suspension varies by about a factor four in the explored parameter range. Surprisingly, this significant change of the intrinsic viscosity is revealed even at low hematocrit (5%). We suggest that this finding may be used to detect blood flow disorders linked to pathologies that affect RBC shape and mechanical properties. This opens future perspectives on setting up new diagnostic tools, with great efficiency even at very low hematocrit. Investigations are also performed on giant vesicle suspensions, and compared to RBCs.
Related publications :
Micro-macro link in rheology of erythrocyte and vesicle suspensions.
V. Vitkova, M. Mader, B. Polack, C. Misbah and T. Podgorski,
Biophys. J. 95 (7), 33–35 (2008)
Dynamics and rheology of a dilute suspension of vesicles : higher order theory.
G. Danker, T. Biben, T. Podgorski, C. Verdier and C. Misbah, Phys. Rev. E76, 041905 (2007)